A rocket has a mass of $100 \,kg$. $90\%$ of this is fuel. It ejects fuel vapours at the rate of $1 \,kg/sec$ with a velocity of $500\, m/sec$ relative to the rocket. It is supposed that the rocket is outside the gravitational field. The initial upthrust on the rocket when it just starts moving upwards is ......... $N$
A rocket has a mass of $100 \,kg$. $90\%$ of this is fuel. It ejects fuel vapours at the rate of $1 \,kg/sec$ with a velocity of $500\, m/sec$ relative to the rocket. It is supposed that the rocket is outside the gravitational field. The initial upthrust on the rocket when it just starts moving upwards is ......... $N$
$0$
$500$
$1000 $
$2000$
A rocket has a mass of $100 \,kg$. $90\%$ of this is fuel. It ejects fuel vapours at the rate of $1 \,kg/sec$ with a velocity of $500\, m/sec$ relative to the rocket. It is supposed that the rocket is outside the gravitational field. The initial upthrust on the rocket when it just starts moving upwards is ......... $N$
$F = u\left( {\frac{{dm}}{{dt}}} \right) = 500 \times 1 = 500\;N$